SJL/J mice have been studied as the model animals for autoimmunological diseases. Recently it was clarified that SJL/J mice have a defect of dysferlin. Human limb girdle muscular dystrophy 2B and Miyoshi myopathy also have a defect of dysferlin. In this study we present the histological and immunohistological changes in the natural course. Histological study revealed that SJL/J mice had inflammatory, degenerative changes, and neurogenic changes in later ages. As for interstitial inflammatory cells, the macrophages were dominant in any age, and in the T cell subset, the CD4+ T cells were more abundant than the CD8+ T cells, and few B cells were seen. The laboratory data showed a high level of creatine kinase in all ages. It is suspected that the inflammatory changes were induced by the primary immunological abnormality or by the defect of dysferlin in SJL/J mice.